Abstracts

Rationale: Psychomotor variant also called rhythmic mid temporal theta of drowsiness (RMTD) is considered to be a benign EEG variant. It is classically described as long runs of rhythmical activity in the range of 5 to 5.6/sec with a maximum over the midtemporal region. These theta waves may appear sharp, flat or notched in appearance and are predominantly seen during light drowsiness. The pattern has been described mainly in adolescents or young adults with a prevalence of 0.1% to 2%. Methods: We reviewed 1459 routine (outpatient and inpatient portable) EEG studies referred to our laboratory from June 2010 through May 2011 for the presence of psychomotor variant. The EEG requisition diagnoses were stroke, seizures, headache, head trauma, altered mental status. The studies showing psychomotor variant were further analyzed for the demographics of the patient (age and sex), its laterality, the state in which it was seen, the EEG requisition diagnosis and available imaging studies.Results: We identified 11 patients (5 males and 6 females) with the presence of RMTD with a mean age of 44 years for a prevalence of 0.1%. In 9 patients, the pattern was seen in drowsiness and in 2 patients was seen during wakefulness. It was bilateral in 9 patients and unilateral (only on the left) in 2 patients. Imaging studies were available for 6 patients and 5 of them were normal with only one showing right mesial temporal sclerosis.Conclusions: Psychomotor variant also called mid temporal theta of drowsiness is considered to be a benign EEG variant with a reported prevalence of 0.1% to 2%. Our prevalence was lower at 0.1%. As it has been reported in the literature, the presence of psychomotor variant is independent of diagnoses. Our findings are in concordance with this. In the literature, it is traditionally reported to be present in adolescents or young adults. We, on the contrary, found it beyond the commonly reported age-group.